Baffles are used in a variety of applications to direct the flow of fluids and gases through tubular members. One such application is for use in the manifolds of heat exchangers. Generally, heat exchangers include a pair of manifolds and a series of tubes interconnected between the manifolds. To optimize the efficiency of a heat exchanger, the flow of a heat transfer fluid, which may be gas or liquid, through the tubes is often controlled by placing baffles within the manifolds, such that separate and parallel flow regions can be established within the heat exchanger by appropriately routing the fluid through the tubes of the heat exchanger.
The prior art has suggested various methods and tools for installing baffles, an example of which is U.S. Pat. No. 5,052,478 to Nakajima et al. Nakajima et al. teach the insertion of partitioning plates through circumferential slots formed in the wall of a heat exchanger manifold. A notable disadvantage of this method is that inserting plates through the manifold wall does not itself positively secure the plates to the manifold. Therefore, the plates must be soldered, brazed or welded to the manifold, or an additional fastening member is required to secure the plates. However, attaching the plates with solder and the like can contaminate the interior of the manifold with foreign matter, such as solder flux. In addition, the presence of slots in the manifold wall substantially weakens the manifold, reducing its capacity to withstand numerous temperature and pressure cycles.
As such, others in the art have proposed various other methods and tools for installing a baffle within a manifold without compromising the structural integrity of the manifold. For instance, commonly-assigned U.S. Pat. No. 4,762,152 to Clausen teaches a tool for installing a baffle within a manifold so as to completely avoid the necessity of cutting slots in the manifold. Baffles installed in this manner are generally cup-shaped, with a closed base and an axially-extending annular sidewall that forms a cavity with the base. The radial thickness of the sidewall increases in thickness in a direction away from the base. These baffles are installed with a tool having a head adapted to be inserted into the recess of the baffles. Once the baffle is appropriately positioned within the manifold, the tool is retracted from the recess, forcing the sidewalls radially outward as the tool is withdrawn. In so doing, the sidewall is forced against the inner surface of the manifold, thus plastically deforming the baffle and manifold so as to secure the baffle in place.
While Clausen teaches an uncomplicated installation tool, others in the prior art have resorted to more complicated tool designs, as evidenced by U.S. Pat. No. 5,165,470 to Maekawa et al., which teaches an installation tool having a narrow shaft threadably connected to a radially larger head that remains within the baffle after installation. The tool must be rotated during installation of the baffle, which considerably complicates the installation process. Further complicating the installation method of Maekawa et al. is the requirement of a stop member that must be inserted with the installation tool to prevent the baffle from being inadvertently removed with the tool. Without the stop member, a newly installed baffle would tend to be removed or at least dislocated while the tool is being retracted. Finally, tools of the type taught by Maekawa et al. can be difficult to initially insert into a baffle, particularly if it is desirable to use such tools on an automated assembly line.
Other installation methods and tools have been suggested by which the necessary radial outward force required to secure a baffle to the wall of a manifold is created by a forward-moving shaft rather than a rearward-moving tool of the type taught by Maekawa et al. and Clausen. For example, Japanese Application No. 63-239062 to Nishishita teaches a tool for installing a bowl-shaped baffle having a closed base and an axially-extending, radially-diverging sidewall of uniform thickness. To secure the baffle in place, this tool applies a radially outward force on the baffle's sidewalls with a radial arrangement of fingers that are mechanically forced radially outward with a rod. The bowl-shaped baffle employed by Nishishita necessarily has a larger diameter than the manifold passage due to the rather mechanically inefficient manner in which the baffle is only locally expanded by the radial fingers. However, this shape renders the baffle difficult to temporarily secure on the tool prior to insertion into the manifold, and also resists and complicates the initial insertion of the baffle into the manifold. Also, localized expansion of the baffle sidewall with the radial fingers can allow leakage if the diameter of the baffle is compromised to facilitate its insertion into the manifold. Finally, such baffles are more prone to becoming dislodged due to the limited extent to which the sidewall is deformed to secure the baffle in place.
Accordingly, it can be seen that an improved method is needed for installing and securing a baffle in a tubular member, such as a heat exchanger manifold. More particularly, such a method should provide for secure attachment of a baffle without compromising the structural integrity of the manifold, employ an installation tool that is capable of readily and securely gripping the baffle prior to and during installation, enable the baffle to be shaped to permit the tool to readily grasp the baffle and thereby facilitate insertion of the baffle into the manifold, provide for uniform securement of the baffle against the walls of the manifold, and enable the tool to be removed without inadvertently removing the baffle with the tool.